1. Field
The disclosed concept relates generally to electrical switching apparatus and, more particularly, to electrical switching apparatus, such as circuit breakers. The disclosed concept also relates to levering assemblies and to position indicator assemblies for circuit breakers.
2. Background Information
Electrical switching apparatus used in power distribution systems are often mounted within a switchgear enclosure either individually or in combination with other switchgear (e.g., without limitation, circuit switching devices and circuit interrupters such as circuit breakers, contactors, motor starters, motor controllers and other load controllers).
Some electrical switching apparatus such as, for example, some medium-voltage and low-voltage circuit breakers, can be relatively large. In order to facilitate movement (e.g., installation; removal; maintenance), some circuit breakers are commonly coupled to draw-out mechanisms which permit such circuit breakers to be drawn out of the switchgear enclosure. Accordingly, such circuit breakers are commonly known in the art as “draw-out” circuit breakers. The circuit breaker may be further supported within a draw-out frame, commonly known in the art as a cassette or chassis. The switchgear enclosure generally includes a number of cells, with each cell being structured to receive a corresponding circuit breaker. The draw-out mechanism includes, for example, a combination of rails and rollers coupled to one or the other, or both, of the sidewalls of the cell and the sides of the corresponding circuit breaker and/or cassette, which is to be drawn into and out of the cell. A levering in assembly (sometimes referred to as a “lev-in” device), which among other components includes a drive screw and drive rack, facilitates levering the circuit breaker into the cassette. Draw-out circuit breakers are described in further detail, for example, in commonly assigned U.S. Pat. No. 7,019,229, which is hereby incorporated herein by reference.
When a draw-out circuit breaker is being levered into a cassette, proper position or travel indication must be displayed. For example, such indication is both required for safety, and used for interlocking of the circuit breaker mechanism and lev-in device. Some lev-in devices include a position indicator for this purpose. However, among other disadvantages, the motion associated with providing the indication is not constant. For example and without limitation, mechanical drive of the position indicator is intermittent, in view of the use of partial gear teeth, cams and/or slots.
There is, therefore, room for improvement in electrical switching apparatus, such as circuit breakers, and in levering assemblies and position indicator assemblies therefor.